high intensity challenges of the fair project oliver boine-frankenheim, gsi, darmstadt

Oliver Boine-Frankenheim, HB2008

High Intensity Challenges of the FAIR Project

Oliver Boine-Frankenheim, GSI, Darmstadt


Nov. 7, 2007: FAIR project start event

Partners signing communiqué:Austria, Germany, Spain, Finland, France, Poland, Romania, Russia, Sweden, Great Britain

German Minister Ms. Schavan on November 7, 2007


• 1400 international participants• 500 international scientists attended the symposium on the Physics of FAIR

FAIR start event


FAIR rings and parameterbaseline layout

100 m

UNILACSIS-18

SIS-100/300

HESR

SuperFRS

NESR

CR

RESR

FLAIR

Radioactive Ion Production Target

Anti-Proton Production Target

Existing facility UNILAC/SIS-18: provides ion-beam source and injector for FAIR

Existing facility UNILAC/SIS-18: provides ion-beam source and injector for FAIR

New future facility: provides ion and anti-matterbeams of highest intensities and up to high energies

New future facility: provides ion and anti-matterbeams of highest intensities and up to high energies

Accelerator Components & Key CharacteristicsRing/Device Beam Energy Intensity

SIS100 (100Tm) protons 30 GeV 4x1013

238U28+ 1 GeV/u 5x1011 (intensity factor 100 over present, short single bunch)

SIS300 (300Tm) 238U92+ 34 GeV/u 2x1010

CR/RESR/NESR ion and antiproton storage rings

HESR antiprotons 14 GeV ~1011

Super-FRS rare isotope beams 1 GeV/u <109

p-linac L=216 m

L=1080 mThis presentation: SIS-18 and SIS-100


Required FAIR beam intensitiesHeavy ions

SIS-18 today* After upgrade After upgrade

(to SIS 100)

SIS 100

Reference ion U28+ / U73+ U73+ U28+ U28+

Maximum energy 0.2 / 1 GeV/u 1 GeV/u 0.2 GeV/u 2.7 GeV/u

Maximum intensity

5x109 / 3x109 2x1010 1.5x1011 5x1011

Repetition rate 0.3 Hz 1 Hz 2.7 Hz 0.7 Hz

Bunch length > 100 ns 50 ns - 60 ns

FAIR specific beam dynamics challenges:o Intensities at the ‘space charge limit’o High beam quality (weak or lost Landau damping)o Long accumulation time (1 s) in SIS-100o Reducing beam loss induced pressure increase

5x1011 U28+

SIS 18

SIS 100 cycle*UNILAC studies: L. Gröning’s talk, Tuesday


SIS-18 intensitiesstatus and upgrade parameters

x / y 150 /50 mm mrad

p

p

dc

10 3 (long. space charge effect on the UNILAC micro-bunches)

Injection energy: 11.4 MeV/u(acceptance)

Challenge: Working point optimization and resonance compensation for low beam loss (< 10 %).

G. Franchetti’s talk on Tuesday

SIS-18

L=216 m

Incoherent space charge tune shift:

Qysc

2NZ 2g f

A020

3B f y yx

≈ 5x109 U28+

≈ 3x109 U73+


U28+ lifetime in SIS-18low beam intensities

1(P) 0c loss

P

kBT

U 28 X U 29 X e

R. Olson et al., J. Phys. B (2004)

loss E 1/ 2

loss E 1Born approximation:

CTMC simulations:

G. Weber, Heidelberg, 2006

Energy [MeV/u]

lifeti

me

[s]

2001

G. Weber 2004

CTMC

Born

Loss of one or more electrons:

(Lifetime)-1:


SIS-18 upgradeControl of the dynamic vacuum pressure

Beam loss mechanisms:U28+ -> U29+ (stripping)U73+ -> U72+ (capture)

dP

dt p

1(P P0)lossNP

Dynamic pressure:

Desorption coefficient:

NEG coated vacuum chambers

Challenges:- increase pumping speed- localize beam loss- minimize desorption

Combined pumping/collimation portsbehind every dipole group.

# desorbed molecules

# incident ions

dE

dx

2

U28+ lifetime in SIS-18 (C. Omet)

N(t)

1.8E10

8E9

60 % loss

270 ms

P.Spiller


SIS-18 upgradenew dual rf system

Bf=0.35 !

φs=450

Bucket filling factor U28+: 2/3V0 [kV] f [MHz] harmonic

MA 40 0.43-2.8 2

Ferrite 16 0.86-4.2 4

Magnetic Alloy (MA) filled rf cavity

For SIS-18 operation with 2.7 Hz theexisting rf voltages are not sufficient.

P. Hülsmann et al.

Additional compact rf cavity system:+ increase rf bucket area+ flattened bunch profiles

Challenges: - Space charge induced voltage reduction: ≈40 %- Bunch stability with space charge- Control of bunch deformation due to beam loading (low Q)


SIS-100 bunch compression

#cavities Voltage [kV] Frequency [MHz] Concept

Acceleration 20 400 1.1-2.7 (h=10) Ferrite

Compression 16 600 0.4-0.5 (h=2) MA (low duty cycle)

SIS 100

L=1080 m

Single bunch formation

8 bunches

‘bunch merging’

pre-compression

rotation

extraction

0.2->1.5 GeV/u

∆Qsc≈ -0.6 !

RF cavity systems in SIS 100:

2-4x1013

5x1011

Particles/bunch bunch length

25 ns29 GeV/u p

60 ns1.5 GeV/u U28+

Final bunchparameters:

rf compressor section (≈40 m)

bunch compressor loaded with 20 MA cores


space charge reduces the effect of beam loading

SIS-100 bunch pre-compressionbarrier rf buckets with beam-loading and space charge

# cavities Rs/cavity [kΩ] Qs fres

acceleration 20 3 10 10f0

barrier 2 1 0.4 1.5 MHz

compression 16 1 2 1.5 MHz

Z lsc

n

igZ0

2002i200

Longitudinal space charge impedance:

Stationary bunch profile from the Haissinski equation (no rf):

s Zl

sc

n

r Rswith

Bunch area increases by 20 % during pre-compression. Longitudinal dilution budget in SIS-100: Factor 2.

Vlasov simulationincluding cavity beam loading andspace charge.


SIS 100 dipole magnetsfull size model from Babcock Noell GmbH

1st Full Size Dipole is ready for testing!

Dipole magnet with elliptical beam pipe

2D/3D field calculations

Superconducting magnet with 4 T/s and Bmax= 1.9 T

P. Spiller, SIS-100, Tuesday afternoon


SIS-100 field quality and beam lossat injection energy 0.2 GeV/u

SIS-100 transverse apertures at injection (0.2 GeV/u)

dynamic aperture

magnetaperture

lattice aperture

beam

High intensity challenges for SIS-100:•Long time scales up to 106 turns (1 s)• Space charge tune shift of ΔQsc=-0.25•‘Thick’ medium energy beams (2/3 filling factor) • Optimized working point for < 5 % loss.

G. Franchetti (2008)

Simulation scan of the SIS-100 dynamic aperture

tune

space chargetune spread

G. Franchetti, SIS-100 technical design report (2008)

Long-term (up to 1 s) 3D particle tracking studieswith ‘frozen’ space charge indicate a space charge limit at 3x1011 U28+ (design 5x1011).


SIS-18 transverse impedance spectrum (200 MeV/u)

wall (smooth)

f0

e-cloud

kicker (x)

kicker (y)

Specific SIS-18/100 impedance issues:- Low frequencies and beam energies- Thin (0.3 mm ) stainless steel pipe (optional corrugated) - Ferrite or magnetic alloy loaded ring components- Distributed collimation system

Doliwa, Weiland (2006)

Ferrite loaded kicker modules

Zsc i

Z0R

020

2

1

b2 i10 M/m‘Space charge impedance’:

Transverse impedances in SIS-18/100

e-clouds ?:

- electrons from residual gas ionization and beam loss.

- e-accumulation: survival rate in bunch gaps ?

- transv. ‘impedance’: Ohmi, Zimmermann, PRL (2000)

- long. impedance: Al-khateeb et al. NJP (2008)

dc: Loss of Landau damping


Resistive (thin) beam pipe in SIS-100Transverse impedance and shielding

Al-khateeb, Hasse, Boine-F., Daqa, Hofmann, Phys. Rev. ST-AB (2007)

SIS 100 transverse resistive wall impedance (200 MeV/u)

Z

2cR

b3d

Transmission coefficient !

In SIS-100 the thin (0.3 mm) beam pipe is the dominant transverse impedance contribution !

Transmission: Structures behind the pipe might contribute !SIS-18: Measured growth rate of the resistive wall instability agrees with impedance formula.


Transverse Impedance Budget with Space Charge

Specific issues for SIS-100:- Long time scales (up to 1 s)- Image current and space charge effects- Long bunches and ‘dc-like’ barrier rf beamsPotential cures:- octupoles and nonlinear space charge (Kornilov et al. PRST-AB 2008)- feedback systems

coasting beam stability boundaries (from dispersion relation)

Challenges:- Octupoles and dynamic aperture- 3D space charge and image current effects

Qincohsc Qcoh

sc s

Head-tail instability in SIS-100 (talk by V. Kornilov this Monday afternoon):-Sacherer’s formula predicts head-tail modes with 70 ms growth rate in SIS-100 !-3D simulation studies including: resistive wall impedance, image currents, space charge, nonlinear rf.-’Mode coupling regime’: (νs: synchrotron tune)

Chromatic damping

Zsc i

Z0R

020

2

1

a2

1

b2

Z Zrw Z

sc


Transverse Schottky signals with space chargeUnderstanding signals from stable beams with space charge

Boine-Frankenheim, Kornilov, Paret, PRST-AB (2008)

fn (n Q0) f0

P( f ) P0(z)

(z)2

The measured Schottky band (upper sideband)with space charge is deformed, but not shifted.

coasting beam (measurement in SIS-18)

Qs

Q

1

coherent betatron frequencies:

Modified Schottky band:

bunched beam (simulation)

Q0 Q0+νs

Qsc

s

1

Central line is not shifted, but synchrotron satellites are. Amplitudes seem to follow thedc results P(z).

Transverse Schottky signals from real or fromcomputer beams provide important informationon the mode structure and Landau damping with space charge.


Decoherence with image currents and space charge3D simulation studies with space charge and impedances

Beam pipe

bunchInitial offset

x (t 0) 0

z

I(z)

dc

Bunch profile

0 L=2πR

Injected bunch in SIS-100 with a transverse offset.

Coherent and incoherent tune spread along the bunch:

coherent tune shift:

Interplay of space charge and image currents: -mode coupling (due to image currents) -persistent bunch modes -halo formation !

Qcoh,incoh (z) Qcoh,incohmax 1

z2

zm2

Qcohsc (z)

i

4qI(z)R

Q00E0

Zsc


Summary

A next design iteration of the FAIR synchrotron facilities has been finalized.(see latest Technical Reports.)

For high intensity operation a number of optimization challenges have still to overcome.

Of outmost importance is to further increase the beam intensity and quality in theUNILAC/SIS-18 injector. SIS-18/SIS-100 high intensity challenges:- Working point and resonance compensation for low beam loss.- Control of the dynamic vacuum pressure for heavy ions.- Complex RF manipulation at high beam intensities.- Control of coherent beam instabilities.

FAIR related talks:V. Kornilov, Coherent instabilities in SIS-100, Monday afternoonG. Franchetti, Space charge resonances in SIS-18, Tuesday afternoonP. Spiller, SIS-100, Tuesday afternoonL. Gröning,Emittance grwoth stdy in the UNILAC, Tuesday morning


in 2016

Thank you !

Austria China Finland France Germany Greece India Italy Poland Slovenia Spain Sweden Romania Russia UK

Observers:Observers:


SIS-18 working point and resonance compensation

N7+

Challenge: Multi-turn injection (MTI) and working point optimization for low beam loss (< 10 %).

G. Franchetti’s talk on Tuesday

high intensity challenges of the fair project oliver boine-frankenheim, gsi, darmstadt

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